DESCRIPTION: (Applicant's Abstract) The overall objective of the research is to continue epidemiological studies related to three major themes on substance use in adolescence and adulthood: (1) the natural history of drug use and developmental patterns of involvement and cessation in the use of drugs; (2) the risk factors for involvement in drugs; and (3) the consequences of using drugs. Risks and consequences include mental health, behavioral, biological, interpersonal and intrapersonal factors. The consequences of interest include consequences for the individual user and for the user's family, in particular, child-rearing practices and children's development. The drugs of interest include cigarettes, alcohol, illicit drugs, especially marijuana and cocaine, and the medically prescribed psychoactives. Stimulated by findings obtained in the current period of support, the goal for the next five-year period is to extend the work in three directions: (1) to investigate further the role of prenatal smoking as a potential risk factor for adolescent smoking, drinking and drug dependence more generally; (2) to study the epidemiology of substance dependence and abuse (comparative phenomenology of dependence for different drug classes and different groups in the population; relationships to stage of drug involvement, treatment, psychiatric symptoms and behavioral problems; familial and historical determinants); (3) to investigate prospectively and developmentally the progression from use to dependence and the comorbidity between drug use, drug dependence and psychiatric symptoms and disorders in adolescence. Three interrelated programs of research will be pursued to achieve these aims: analyses of a large national longitudinal sample of mother-child dyads, analyses of multiple waves of the National Household Survey on Drug Abuse, and the implementation of a new longitudinal cohort-sequential study of adolescents. This program of research will address issues of crucial importance for understanding the etiology of drug use and dependence among young people, the transition from use to abuse, and the developmental course of substance dependence and psychiatric comorbidity. Understanding these issues is crucial for the development of effective prevention and treatment interventions. Several components of the program represent innovative activities in epidemiological research carried out on general population samples.